Clinical Outcomes, Mortality Risk Factor of RSV, Influenza in Hospitalized Adults

Respiratory syncytial virus (RSV) and influenza pose serious health risks, especially for older adults and those with comorbidities. Older adults hospitalized with RSV infections are at a higher risk of dying within 90 days of hospitalization than patients admitted with influenza B, but at a similar risk as those admitted with influenza A, a study finds.¹

The study highlights the severe effects of RSV, which was significantly found to contribute to disease and death among older adults. | Image credit: Kateryna - stock.adobe.com

The multicenter observational cohort study is published in Open Forum Infectious Diseases.

“This highlights the severity and detrimental effects of RSV, which are similar to or worse than those of influenza A and B,” wrote the researchers of the study. “The results underscore the potential life-threatening nature of RSV. Harmonizing in-hospital testing strategies, increasing awareness, and advocating for targeted RSV vaccinating efforts among high-risk groups and older adults is important.”

RSV is a significant pathogen among adult patients admitted to the emergency department (ED), especially among those with underlying medical conditions.² In the current study, the researchers aimed to analyze and compare the clinical characteristics, outcomes, and mortality risk factors in adults hospitalized with RSV or influenza A/B.¹

The cohort study examined adults hospitalized with RSV, influenza A, or influenza B across 2 major Danish hospitals between 2016 and 2020. Eligible patients were diagnosed within 48 hours of admission using validated viral assays, including oropharyngeal or nasal swabs, sputum, and bronchoalveolar lavage samples. Clinical data were collected, including patient demographics, comorbid conditions, respiratory parameters, and clinical outcomes.

A total of 1150 individuals were identified during the study period, yielding 988 patients after exclusion. Of these patients, 353 (36%) were hospitalized with RSV, 347 (35%) with influenza A, and 288 (29%) with influenza B. Patients hospitalized with RSV were of similar median age to those with influenza B, though both groups were older than those with influenza A. Comorbidities were more prevalent among patients with RSV, with 82% having at least 1 condition, compared with 72% of patients with influenza A and 74% of patients with influenza B.

Hypertension was the most common comorbidity, followed by congestive heart failure (CHF) and chronic obstructive pulmonary disease (COPD), with CHF and COPD occurring more frequently in patients with RSV than in those with influenza A or B. Additionally, 41% of patients with RSV had pneumonia, a higher rate than in influenza A (29%) and influenza B (24%) cases. Dyspnea was also more common in patients with RSV, affecting 64%, compared with 51% and 39% in influenza A and B, respectively.

RSV infection was associated with an increased all-cause mortality rate within 90 days compared with influenza B (OR, 2.16; 95% CI, 0.84-2.29; P = .21). Additionally, increasing age and present pneumonia were independent mortality risk factors in patients with RSV.

The researchers noted several limitations; variability in testing protocols across hospital sites and years, along with the absence of standardized guidelines for RSV testing, may have introduced sampling bias. Additionally, the lack of data on immunosuppressive disorders and vaccination status limited the study’s ability to assess the impact on clinical outcomes. A significant portion of influenza B cases occurred during the 2017–2018 season, which may have affected the generalizability of these findings, as this strain is not typically included in vaccines for older adults.

Despite these limitations, the researchers believe the study highlights the severe effects of RSV, which was significantly found to contribute to disease and death among older adults.

“Further recognition of RSV as an important pathogen in severe acute respiratory infections is pivotal for better testing strategies, targeted treatment, including antiviral trials, and discontinuation of antibiotics, leading to better antibiotic stewardship, and vaccination strategies,” wrote the researchers.

References

1. Clausen CL, Egeskov-Cavling AM, Hayder N, et al. Clinical manifestations and outcomes in adults hospitalized with respiratory syncytial virus and influenza a/B: A multicenter observational cohort study. Open Forum Infect Dis. 2024;11(10):ofae513. Published 2024 Sep 20. doi:10.1093/ofid/ofae513.

2. Steinzor P. Adult RSV hospitalizations: Clinical characteristics, risk factors for severe outcomes. AJMC. Published October 4, 2024. Accessed October 21, 2024. https://www.ajmc.com/view/adult-rsv-hospitalizations-clinical-characteristics-risk-factors-for-severe-outcomes.